the citrus white fly: injury. " 11 



Distribution in the United States. 



The citrus white fly in the United States has been recorded as 

 existing under natural conditions in Florida, southern Georgia, South 

 Carolina, Alabama, Mississippi, Louisiana, and Texas. In 1907 it 

 was discovered in two localities in California, following which stren- 

 uous efforts were made toward its eradication. Recent reports* 

 state that the insect has reappeared in one of these districts. In 

 addition to the above citations the pest has long been laiown from 

 greenhouses in many northern States. 



The importance of the white fly as a citrus fruit tree pest is shown 

 almost exclusively in those Gulf Coast States where citrus fruits are 

 produced commercially. Although oranges are being grown quite 

 extensively in Louisiana and Texas, and to some extent in Alabama, 

 it is in Florida that the orange-growing industry stands forth as a 

 great and most important one. The distribution of the white fly in 

 Florida has become so general that it has been reported by Morrill 

 and Back ^ as occurring to a greater or less extent in all but two of 

 the 17 important citrus fruit-growing counties. All important agi- 

 tation and efforts toward control have originated in this one State. 

 The close association of this insect pest with the orange and grape- 

 fruit industry of Florida has led to its frequently being called the 

 ''Florida white fly" when referred to in other parts of the United 

 States. 



Injury. 



The white fly is the most serious enemy of citrus trees in the Gulf 

 Coast States. Considering the extent of its injury, together with the 

 difficulty experienced in its control, it stands as without doubt the 

 most serious pest to citrus-fruit production in the entne United 

 States. Injury from the white fly may be considered from two 

 standpoints — direct injury to the tree by loss of vitality through 

 removal of sap, or injury produced from the presence on the leaves, 

 branches, and fruit of the sooty-mold fungus which flourishes on the 

 honeydew seci^etions from the white fly. Although the injury due 

 to loss of sap is undoubtedly considerable, it is of small importance 

 compared with the injury directly or indirectly resulting from the 

 fungous growth, and were it not for this secondary consideration the 

 present fear to the citrus-fruit grower of white-fly infestation would 

 be largely eliminated. The sooty mold remains in a more or less 

 nascent period during the winter months and early spimg, but later 

 develops rapidly, so that with the approach of summer it has heavily 

 coated those trees severely infested with the white fly. 



The fungus naturally follows the distribution of the honeydew, 

 which is prevalent especially on the upper surface of the leaves and 



» Monthly Bui. Cal. State Comm. Hort., vol. 1, no. 6, pp. 242-243, 1912. 

 2 Bui. 92, Bur. Ent., IT. S. Dept. Agr., pp. 25-26, 1911. 



